Sealing means for vacuum vessels



Sept. 29, 1959 F. HARDERS SEALING MEANS FOR VACUUMWESSELS 2 Sheets-Sheet l Filed March ll, 1957 Sept. 29, 1959 F. HARDERS 2,906,521

SEALING ME-ANS FOR VACUUM VESSELS Filed March 11, 1957 2 sheets-sheet 2 /N VEN TOR.

im MM United States Patent Oiice 2,906,521 Patented Sept. 29, 1959.

snALnvG MEANS Fon VACUUM vEssELs Fritz Harders, Post Ergste uber Schwerte, Germany, assignor to Dortmund-Hrden' Huttenunion Aktiengesellschaft, Dortmund, Germany Application March 11, 1957, Serial No. 645,037 Claims priority, application Germany March 16, 1956 z claims. (c1. zas- 34) Vessels for removing gases from molten metals, especially iron and steel, have been developed in which-the metal is degasied either continuously or periodically. In these vessels which are provided with an air-tight steel casing leakages are particularly liable to occur in the region of the inlets and outlets for the metal. This applies particularly to vacuum vessels in which a pipe connection, which consists of a steel casing lined with refractory material, leads downwardly from the bottom of the vessel. The free end of the pipe connection which dips into the molten metal to be degasied is protected on the outside by an annular body of refractory material which surrounds the metal casing. Since the refractory material of the pipe connection is always in contact both externally and also internally with the metal to be degasitled, leakages can easily occur at this place and cause the yvacuum to be broken. In the case of vacuum vessels through which the metal passes from a pot situated above the vacuum Vessel and is thereby degasied, the danger zone is situated not only vat the end of the pipe connection leading from the bottom of the vacuum vessel but also in the region where the metal enters the vacuum vessel.

The present invention relates to sealing means for the inlets and outlets for the molten metal in vacuum vessels used for the degasication of metals. The seal is made by inserting a metal plate or tubular member in the refractory lining in the vicinity of the inlet and outlet. One edge or end of the plate or tubular member is connected vacuum-tightly to the casing of lthe vessel or of its inlet or outlet connection and cooled at this place. The free edge or end of the plate or tubular member on the `other hand is so disposed that it comes into contact with the liquid metal by which it is melted to the extent permitted by the cooling of the other edge or end. In this way there is formed a seal of molten metal, which is, therefore, absolutely vacuum-tight. The metal seal, which is disposed in the region of the inlet and outlet, and the end of which in Contact with the liquid metal is melted also serves to prevent the gases from passing through the liquefied material owing to the pressure difference existing at these places. The metal plates or tubular members are preferably made of the same material as the metal to be degasied.

Apparatus for degasifying metals in accordance with the invention are illustrated, by way of a number of constructional examples, in the accompanying drawings, in which:

Figure l is a vertical section through a fixed vacuum vessel which is charged with metal and emptied by raising and lowering a ladle;

Figure 2 shows on a larger scale a section through the bottom outlet connection of the vacuum vessel shown in Figure l;

Figure 3 is a Vertical section through a fixed vacuum vessel through which the metal to be degasied flows;

Figure 4 shows on a larger scale part of the vessel illustrated in Figure 3, and

Figure 5 shows, also on a larger scale, a section through the tubular bottom outlet connection of the vacuum vessel illustrated in Figure 3.

Referring to the drawing, the vacuum installation which is diagrammatically illustrated in vertical section in Figure 1 consists of a vacuum vessel 1 which is disposed in a xed position on a platform B and is connected to a vacuum pump P. The vacuum vessel has a lining 2 of refractory material which is enclosed air-tightly by a metal casing 3. The space 4 within the vessel which is to be evacuated can be relatively small.

A pipe connection 5 opens into the bottom of the vessel 1 and the lower end of the pipe dips into the molten metal S in a ladle 6. Portions of the melt S are successively drawn up into the vacuum vessel 1 and after being degasitied are again discharged from it by raising and lowering the ladle which is disposed on the hydraulically operated platform 7 of a carriage 8. This evacuating process forms the subject-matter of the patent application No. 633,971, U.S.A.

Figure 2 shows on a larger scale the seal for the bottom pipe connection 5 of the vacuum vessel 1. The pipe connection 5 which leads from the bottom of the vacuum vessel consists of a sheet metal casing 9 which is connected vacuum-tightly to the casing 3 of the vacuum vessely 1, and is provided on the inside with a refractory lining 10'. The free end of the pipe connection which dips into the melt S to be degasied is also surrounded on the outside by an annular body 11 of refractory material. Between the lining 10 and body 11 is disposed a casing 970i steel over which an annular sealing body 12 is inserted. One end of this sealing body is connected vacuum-tightly to an annular cooling body 13 which surrounds vacuum-tightly'the casing 9 of the pipe connection S.

When the outer end of the pipe connection 5 Iwhich is protected by the refractory annular body 11 is dipped into the metal to be evacuated, for example into molten iron, apiece at the end of the pipe connection is melted away from the casing 9 and from the sealing body 12 which surrounds it, namely to the extent permitted by the cooling body 13, surrounding the sheet metal casing 9 of the pipe connection. Owing to the liquid metal in the annular space 14, air under atmospheric pressure is prevented with certainty from penetrating between the sheet metal casing 9 and the refractory lining 10 of the pipe connection 5.

The lining of the parts to be sealed, for example, the pipe connection 5, is preferably made of a rammed refractory mass, the mass being, at the same time, reinforced with metal insertions which are connected to the casing, for example of the pipe connection 5. U-shaped iron wires 15, which are welded to the casing 9 to the cooling body 13, can be used, for example, for reinforcing the outer annular body 11. Short rods 16, of which one end is again connected to the casing 9, can be embedded in the refractory lining of the pipe connection 5. T-shaped rods have proved to be particularly suitable as reinforcement. The reinforcements ensure that the rammed mass is firmly held together. The reinforcements also contribute towards increasing the cooling of the lining.

Figure 3 of the drawings illustrates in vertical longitudinal section a vacuum vessel which may be used for a continuous degasication process. A pot 17, the casing 18 of which is welded vacuum-tightly to the casing 3 of the vacuum vessel 1 is disposed on the vacuumvessel 1. The molten material S to be degasied passes through an outlet 19 in the bottom of the pot 17 and enters the chamber 4 of the vacuum vessel through an inlet passage 20. It leaves the chamber 4 through a pipe connection 21 leading from the bottom of the vessel from which the degasied metal runs into a ladle 22 or a mould.

In the installation described above the inlets and outlets where there is a danger of leakage occurring are in the region of the bottom opening 19 of the pot 17 and at the end of the pipe connection 21 leading from the bottom of the vacuum vessel 1. These places are made vacuum tight in accordance with Ithe invention in the following manner.

Figure 4 illustrates on a larger scale the connection of the pot 17 to the vacuum vessel 1.

The metal body which effects the seal consists, in this case, of a truncated metal cone 23, the end of larger cross-section being welded at 24 to the casing 3 of the vacuum vessel. The free end 25 of the cone 23, which end is of smaller cross-section, projects beyond the refractory lining 26 of the pot 17 into the interior of the pot. In the region of its larger cross-sectional area which is air-tightly connected to the casing of the vacuum vessel, the cone 23 is cooled from the outside by an annular pipe 27. The outlet opening 19 of the pot 17, which is disposed within the cone 23, is surrounded by a refractory in contact with the metal ilowing out. A cooling ring 33 surrounds the place where the sealing disc is connected to the casing 29. The lower part 32 of the refractory lining of the pipe connection is preferably constructed in such a way that it can easily be changed.

I claim:

1. Means for sealing the outlet pipe from a vacuum vessel for degasifying molten metal, said vessel and outlet pipe comprising a metal casing and a refractory lining in said casing and said outlet pipe having a body of refractory material surrounding its free end, said sealing means consisting of a tubular metal member interposed between said casing and said outer refractory body, one

t end of said tubular member being air-tightly connected to mass which is inserted or rammed into the cone 23. The

outlet through the cone 23 is again made vacuum-tight owing to the fact that the free end 25 of the cone projects into the pot 17 and is melted by the liquid metal to the extent permitted by the cooling pipe 27. The zone of the outlet where there is a danger of leakage is always surrounded by liquid metal.

Figure 5 illustrates a seal for the pipe connection 21 illustrated in Figure 3 in which the metal is degasied as it flows through the vessel.

In this case also the pipe connection 21 is surrounded by a metal casing 29 and lined on the inside with refractory mass 30. The pipe connection must be made so long that the column of metal within it establishes pressure equalisation between the atmosphere and the space 4 within the vacuum vessel. The pipe connection is sealed by an annular disc 31 which is inserted in the lower part 32 of its refractory lining and is made of metal. .The crosssectional area of the pipe decreases below this disc, so that the section above it always remains filled with liquid metal and the pressure in the metal there is always at least as great as the atmospheric pressure. At its outer periphery the annular disc 31 is welded to the casing 29 of the pipe connection 21, whereas its inner periphery is always said casing, and the other end of said tubular member being free to contact molten metal in which said outlet pipe is immersed, and cooling means adjacent said one end of said tubular member.

2. Means for sealing the outlet pipe from a vacuum vessel for degasifying molten metal, said vacuum vessel and outlet pipe comprising a metal casing and a lining of refractory material Within said casing, said sealing means comprising an apertured metal disc embedded in said refractory lining of said outlet pipe, the inner periphery of said disc being welded to said casing, one end of said disc being free to contact molten metal in said pipe, and means adjacent to and in interconnection with the outer periphery of said disc for cooling said outer periphery.

References Cited in the tile of this patent UNITED STATES PATENTS 1,507,852 Pleukharp et al Sept. 9, 1924 1,931,144 Gilbert Oct. 17, 1933 2,115,535 ONeil Apr. 26, 1938 2,126,808 Phillips Aug. 16, 1938 2,186,718 Ferguson Ian. 9, 1940 2,544,598 Kalina Mar. 6, 1951 2,734,240 Southern Feb. 14, 1956 2,784,961 Coupette et al Mar. l2, 1957 2,837,790 Rozian June 10, 1958 FOREIGN PATENTS 36,792 Norway Dec. 31, 1923 469,762 Canada Nov. 28, 1950 743,348 Great Britain Jan. 1l, 1956 

